AP Biology: Speciation Patterns Practice Questions
Practice speciation patterns with original AP Biology multiple-choice questions. Each item connects reproductive isolation, gene flow, population divergence, and evolutionary evidence with a clear explanation.
Free original practice questions for study purposes. Open Exam Prep is an independent study resource and is not affiliated with, endorsed by, or sponsored by the makers of AP Exams.
advertisement
Answer the questions below — you get instant feedback and a full explanation for each.
1. A river changes course and separates one lizard population into two groups. Over many generations, the groups accumulate genetic differences and no longer mate successfully when they meet. Which pattern is most directly described?
Explanation. Allopatric speciation begins when a geographic barrier reduces gene flow. Mutation, drift, and selection can then cause separated populations to diverge until reproductive isolation evolves.
2. A plant lineage doubles its chromosome number, making it reproductively isolated from the original diploid population while living in the same area. Which mechanism best explains this rapid speciation event?
Explanation. Polyploidy can create instant reproductive isolation in plants without geographic separation, so it is a common mechanism of sympatric speciation.
3. Several bird species on an island chain evolved from one ancestral species and now have different beak shapes matched to different food sources. Which pattern does this best illustrate?
Explanation. Adaptive radiation occurs when one lineage diversifies into multiple species that occupy different ecological niches, often after colonizing new habitats.
4. Which observation would most strongly support sympatric speciation rather than allopatric speciation?
Explanation. Sympatric speciation occurs without a geographic barrier. Evidence that isolation evolved while populations overlapped geographically supports that pattern.
5. In a hybrid zone, two closely related species mate where their ranges overlap. Which outcome would reinforce reproductive isolation?
Explanation. Reinforcement can occur when hybrids have reduced fitness. Natural selection then favors traits that reduce interbreeding between the two groups.
6. A phylogenetic tree shows many short branches splitting from a single ancestral node soon after colonization of a new lake. Which interpretation best fits this pattern?
Explanation. Many closely spaced branching events from a common ancestor are consistent with rapid diversification, such as adaptive radiation into newly available niches.
7. Two insect populations feed on different host plants in the same field. Mating usually occurs on the host plant, so gene flow decreases even though the populations overlap. Which process could this promote?
Explanation. If host preference reduces mating between groups in the same area, ecological specialization can lower gene flow and promote sympatric divergence.
8. Which condition makes allopatric speciation more likely?
Explanation. Allopatric speciation depends on reduced gene flow caused by geographic separation, allowing populations to diverge independently.
9. A small group of colonizing fish reaches an isolated pond. Over time, drift and local selection make it different from the source population. Which idea is most relevant to this early divergence?
Explanation. The founder effect occurs when a new population begins from a small, nonrepresentative sample of the original population, which can accelerate divergence when gene flow is limited.
10. Which statement best distinguishes gradualism from punctuated equilibrium?
Explanation. Gradualism and punctuated equilibrium are models for the tempo of evolutionary change. They differ mainly in whether change is steady or concentrated in relatively rapid bursts.
11. A researcher wants to test whether two populations are separate biological species. Which evidence is most directly relevant under the biological species concept?
Explanation. The biological species concept emphasizes reproductive compatibility. Reduced ability to produce viable, fertile offspring supports species separation under this concept.
12. Two populations have some gene flow, but strong selection favors different traits in different habitats. What is a reasonable prediction?
Explanation. Gene flow tends to homogenize populations, but divergent selection can still promote differences when it is strong enough. Speciation is a balance among gene flow, selection, drift, and reproductive isolation.
📘 Want a full structured course and official-style practice tests? Browse top-rated AP Exams prep books and courses. Some links are affiliate links; we may earn a commission at no cost to you.
advertisement
FAQ
What speciation patterns should I know for AP Biology?
Know allopatric speciation, sympatric speciation, adaptive radiation, reinforcement, hybrid zones, gradualism, and punctuated equilibrium.
How are allopatric and sympatric speciation different?
Allopatric speciation involves geographic separation that reduces gene flow. Sympatric speciation occurs without geographic separation, often through polyploidy, habitat preference, or sexual selection.
Why does gene flow matter in speciation?
Gene flow moves alleles between populations and tends to reduce divergence. When gene flow is reduced or selection is strong enough, populations can diverge and eventually become reproductively isolated.